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Water Reticulation Benchmark

Water reticulation is water distribution network which is delivered to the consumers. The distribution came from the pressure created from the source and delivered to its destination. Below is an example of the calculation and benchmark with MiTS software.

Project File  #

Provided a project file and the spreadsheet as your reference. 

Diagram below displays the common terms used in water reticulation. 

Hydraulic Grade Line (HGL)     

= Fix Head – Head Loss

Residual Pressure                       

= Hydraulic Grade Line – Highest Supply Level – Head Loss

Tank Water Level                     

=  Height from Ground Level to Tank Water Level

Highest Supply Level             

= Ground Level + Tank Water Level 

Head Loss                                 

= Using Hazen William equation
(Manual Headloss Calculation Benchmark)

 

Peak Flow #

Peak flow or also known as domestic flow. It is calculated for water distribution for domestic uses (residential, school, commercial etc.). Water demand is multiplied with peak factor (2.5) to determine the flow. 

i. Example on Pipe 3 in Nodes for Peak Calculation

Flow (LPS) = Water Demand x Peak Factor

= |--0.144696211458333| x 2.5

= 0.3617 LPS

Calculation of Flow in Pipes for Peak Calculation in Spreadsheet
Calculation of Flow in Pipes for Peak Calculation in MiTS

Velocity (m/s) = Q/A

$$ =\frac{\displaystyle\frac{0.3617}{1000}}{\mathrm\pi0.075^2} $$

= 0.0205 m/s

Velocity calculation in spreadsheet
Velocity calculation in MiTS

$$ \mathbf{Energy}\boldsymbol\;\mathbf{Slope}\boldsymbol\;\boldsymbol(\mathbf m\boldsymbol/\mathbf{km}\boldsymbol)\boldsymbol\;=\;\sqrt[27]{\frac{\mathrm V}{\mathrm k\;\mathrm C\;{({\displaystyle\frac{\mathrm D}4})}^{0.63}}}^{50}\;\times\;1000 $$

(you may refer here)

$$ =\sqrt[27]{\frac{0.0204703}{0.85\;\times\;100\;\times\;{({\displaystyle\frac{0.15}4})}^{0.63}}}^{50}$$

= 0.009185 m/km

Energy Slope (m/km) calculation in spreadsheet
Energy Slope (m/km) calculation in MiTS

 

Head Loss (m) = Sf x L

$$ =\frac{0.009185\;\times\;118.7105}{1000} $$

= 0.00109 m

Headloss calculation in Spreadsheet
Headloss calculation in MiTS

ii. Example on Pipe 1 in Pipes for Peak Calculation

HGL = Fix Head – Head Loss

= 60 – 0.002

= 59.998 m

HGL calculation in Spreadsheet
HGL calculation in MiTS 

HSL = Ground Level + Tank Water Level

= 33.22 + 0

= 33.22 m

HSL calculation in Spreadsheet
HSL calculation in MiTS

Residual Pressure = HGL – HSL

= 59.998 – 33.22

= 26.778 m 

Residual Pressure calculation in Spreadsheet
Residual Pressure calculation in MiTS

 

Fire Calculation #

Fire calculation is the calculation with hydrant assigned in the design. The purpose of it is to make sure whether the water distribution is sufficient to cater during fire breakout, even at the lowest pressure. The value usually used for water demand in fire calculation is 22.7 LPS.

i. Example on Pipe 3 in Nodes for Fire Calculation

Flow (LPS) = (Water Demand x Fire Factor) + Average Flow

= (22.7 x 1) + 0.145

= 22.845 LPS

Flow calculation in Spreadsheet
Flow calculation in MITS

Velocity (m/s) = Q/A

$$ =\frac{\displaystyle\frac{22.84}{1000}}{\mathrm\pi0.075^2} $$

= 1.292 m/s

Velocity calculation in Spreadsheet
Velocity calculation in MiTS

$$ \mathbf{Energy}\boldsymbol\;\mathbf{Slope}\boldsymbol\;\boldsymbol(\mathbf m\boldsymbol/\mathbf{km}\boldsymbol)\boldsymbol\;=\;\sqrt[27]{\frac{\mathrm V}{\mathrm k\;\mathrm C\;{({\displaystyle\frac{\mathrm D}4})}^{0.63}}}^{50}\;\times\;1000 $$

$$ =\sqrt[27]{\frac{1.292}{0.85\;\times\;100\;\times\;{({\displaystyle\frac{0.15}4})}^{0.63}}}^{50}$$

= 19.80 m/km

Headloss (m/km) calculation in spreadsheet
Headloss (m/km) calculation in MITS 

Head Loss (m) = Sf x L

= 19.80 x 118.71 / 1000

= 2.35 m

Headloss calculation in Spreadsheet
Headloss calculation in MiTS 

ii. Example on Pipe 1 in Pipes for Fire Calculation

HGL = Fix Head – Head Loss

= 60 – 1.19

= 58.81 m

HGL calculation in Spreadsheet
HGL calculation in MiTS 

Residual Pressure = HGL – GL

= 58.81 – 33.22

= 25.59 m

Residual Pressure calculation in Spreadsheet
Residual Pressure calculation in MiTS

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